games.groups.yahoo.com/group/tenra-rpg
This is the website dedicated to the Tenra Bansho Zero mailing list. It is the place for the latest information on the game. If you're interested, subscribe! It's free, and there's no spam.

www.j-rpg.com
Andy Kitkowski's site for information and reviews of various Japanese RPGs, including other RPGs by F.E.A.R.

www.fear.co.jp
The official website of F.E.A.R, the company that publishes Tenra Bansho Zero in Japan.

www.tenra.net
The official Japanese support site of Tenra Bansho, unfortunately a little out of date.

www.sasugabooks.com
A bookstore in Boston, MA which orders Japanese RPGs (and of course manga, anime, CDs and books, etc) and delivers them anywhere in the world, including Tenra Bansho Zero. Do a search for "Tenra Bansho" (they list it as "Tenra Bansho Rei"). They can special order just about anything, just email them.